exotic and invasive species

native species

occur naturally within a region or ecosystem without human transport

exotic (non-native, alien) species

introduced intentionally or unintentionally beyond natural range

invasive species

exotic species that establish, spread rapidly, and cause ecological, economic, or social harm

noxious species

species legally designated as harmful to agriculture, natural resources, or human interests

nuisance species

native species that cause conflicts, hazards, or management issues

poison ivy, raccoons, white-tailed deer, honey mesquite, and juniper

examples of nuisance species

poison ivy

native but forms dense patches and cause allergic reactions

raccoons

native but become urban/suburban pests (trash raids, chicken coops)

white-tailed deer

native but overabundant in many suburban areas, causing browsing damage and vehicle collisions

honey mesquite and junipers

can overtake their native ranges, increasing in density and transitioning grasslands to shrublands and woodlands

population dynamics or human-wildlife interactions

unlike invasives, nuisance species aren’t introduced; problems stem from…

livestock, crops, weeds, and pests

settlement of North America brought _____

modern globalization

accelerates movement via shipping, horticulture, pet trade, aquaria, and tourism

biodiversity loss

invasive species are the second leading cause of ______, behind habitat destruction

$120 billion

U.S. economic impact exceeds _____ annually due to crop losses, infrastructure damage, and control efforts

agriculture, erosion control, biocontrol, game species, and aquaculture

exotic and invasive species are intentionally introduced through…

Johnson grass, bermudagrass, and alfalfa

exotic and invasive species that were introduced through agriculture

kudzu, saltcedar, and Chinese tallow

exotic and invasive species that were introduced through erosion control

cane toad and mongoose

exotic and invasive species that were introduced through biocontrol

pheasants and carp

exotic and invasive species that were introduced through game species

tilapia and Asian carp

exotic and invasive species that were introduced through aquaculture

shipping ballast water, wood pallets and packing materials, contaminated nursery stock, pet and aquarium releases, bucket biology, garden escapes, and hurricane/storm releases

exotic and invasive species are accidentally introduced through…

zebra mussels and European green crab

exotic and invasive species that were introduced through shipping ballast water

emerald ash borer and ASB beetles

exotic and invasive species that were introduced through wood pallets and packing materials

weeds and fungal pathogens

exotic and invasive species that were introduced through contaminated nursery stock

Burmese python, lionfish, and giant goldfish

exotic and invasive species that were introduced through pet and aquarium releases

anglers illegally moving baitfish

exotic and invasive species that were introduced through bucket biology

Japanese honeysuckle, pivet, and lantana

exotic and invasive species that were introduced through bucket biology

escaped aquaria fish during storms

exotic and invasive species that were introduced through hurricane/storm releases

natural and human-assisted spread

secondary spread of exotic and invasive species

rivers, wind, and wildlife

natural spread via…

boats, ATVs, livestock feed, and vehicles

human-assisted spread through…

highly reproductive, early maturity, long breeding season, generalist diet, habitat tolerance, high dispersal ability, and rapid growth

biological traits ot exotic and invasive species

enemy release hypothesis, evolution of increased competitive ability, and propagule pressure

types of ecological mechanisms

enemy release hypothesis

invaders escape predators/disease from their native range, allowing unchecked growth

evolution of increased competitive ability (EICA)

invaders evolve to invest more in growth/reproduction in the absence of natural enemies

propagule pressure

frequent or large introduction events increase establishment success

fragmentation and land-use change

create openings for colonization

fire suppression

aids invaders like tallow and cedar

climate change

enables tropical species to expand northward

fragmentation, land-use change, fire suppression, and climate change

types of human influence

disturbance regimes, ecosystem types, edge effects, and resource pulses

examples of ecosystem susceptibility

distrurbance regimes

disturbed sites are invasion hotspots

stable, intact ecosystems are less vulnerable

roadsides, overgrazed rangelands, and logged forests

examples of disturbance regimes

islands, freshwater systems, and rangelands

ecosystem types

islands

lack predators; high extinction risk after invasion

freshwater systems

few barriers and highly invasible

rangelands

fire suppression and grazing allow non-native grasses to establish

edge effects

edges promote seed spread, light availbility, and altered microclimates

honeysuckle, pivets and nandina

suburban edges are home for…

resource pulses

nutrient fluxes from agriculture or storms benefit fast-growing invaders

competition, predation, and disease transmission

ecological impacts of invasive species

competition and predation

displace native fauna and direct predation

disease transmission

exotic fungi, viruses, and parasites decimate native populations

saltcedar, zebra mussels, and cogongrass and cheatgrass

invasive species that alter habitat

saltcedar

deep-rooted, pulls salts upward and increases soil salinity

reduces riparian habitat quality for bats, amphibians, and waterfowl

zebra mussels

clear water which increases aquatic plant growth which shifts food webs

biofueling damages infrastructure

cogongrass and cheatgrass

create continuous fine-fuel beds which increase fire frequency/intensity

fire-tolerant which outcompete natives post-fire

hybridization

genetic impact of invasive species

hybridization

threatens uniqueness of native species

trophic cascades

invaders disrupt energy flow and cause multi-trophic declines

$1.5 billion annual damage

feral hogs cause ____ nationwide; >$230 million in Texas

zebra mussels

increase maintenance costs for municipal water systems

invasives

reduce recreation quality and tourism revenue

invasive mosquitos

increase vector-borne disease risk

european starling, feral hogs, and nutria

terrestrial invasive animals

european starling

nest competition, crop damage, and disease

feral hogs

rooting damage, predation on eggs/fawns, widespread in Texas

nutria

marsh destructions, levee erosion, competition with muskrats

zebra mussels, Asian carp, and lionfish

aquatic invasive species

zebra mussels

infrastructure clogging and plankton depletion

Asian carp

filter-feeding disrupts fish recruitment and leaping hazard

lionfish

reef predator and decimates juvenile fish populations

kudzu, saltcedar, Chinese tallow, and cogongrass

invasive plants

kudzu

smothers vegetation and increases fire risk

saltcedar

alters hydrology, increases salinity, and impacts riparian ecosystems

Chinese tallow

prairie displacement and loss of biodiversity

cogongrass

forms monocultures and hyper-flammable

eDNA, remote sensing, and public reporting

tools for prevention and early detection of invasive species

Clean, Drain, Dry; Don’t Move Firewood; and Habitattitude

outreach of prevention and early detection of invasive species

trapping, cutting, mowing, and water drawdowns

mechanical control

herbicides and pesticides

chemical control

cost, repeated treatments, and environmental risk

limitations of mechanical and chemical controls

biological control

natural enemies used for population suppression

restoration and rehabilitation

replace invaders with natives, hydrology restoration, and prescribed fire

long-term monitoring

for restoration and rehabilitation, _____ is critical

legislation and policy

lacey act, NISA, executive order 13112

TPWD/TDA invasive species regulations

public engagement

volunteer removal events, citizen science, and landowner outreach

adaptive management

promote ecosystem resilience and anticipate climate-driven invasions

education campaigns, ethical stewardship, and community science

public awareness and citizen engagement

education campaigns

critical to prevent new invasions

ethical stewardship

no pet releases and no planting known invasives

community science

enhances early detection and reporting

gene drives, improved eDNA, drone-based detection, international coordation, ecosystem resilience, and long-term restoration

future directions of exotic and invasive species management

managed eecosystem services, game and recreation, cultural value, and controversial benefits

positive ecological roles of some exotics

contextually

ecological impacts must be evaluated ____, not categorically